llvm-6502

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History

Reid Spencer 0a262ba7c3 For PR616: These patches make threading optional in LLVM. The configuration scripts are now modified to accept a --disable-threads switch. If this is used, the Mutex class will be implemented with all functions as no-op. Furthermore, linking against libpthread will not be done. Finally, the ParallelJIT example needs libpthread so its makefile was changed to always add -lpthread to the link line. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@23003 91177308-0d34-0410-b5e6-96231b3b80d8		2005-08-24 10:07:20 +00:00
..
Unix	Implement sys::SetInterruptFunction on Unix, stub it on win32 so that the	2005-08-02 02:14:22 +00:00
Win32	It's dangerous coding on Mondays.	2005-08-02 03:26:32 +00:00
DynamicLibrary.cpp
LICENSE.TXT
ltdl.c
ltdl.h	Eliminate tabs and trailing spaces.	2005-07-27 05:53:44 +00:00
Makefile
MappedFile.cpp	Remove vim settings from source code; people should use llvm/utils/vim/vimrc	2005-05-05 22:33:09 +00:00
Memory.cpp	Remove vim settings from source code; people should use llvm/utils/vim/vimrc	2005-05-05 22:33:09 +00:00
Mutex.cpp	For PR616:	2005-08-24 10:07:20 +00:00
Path.cpp	For PR495:	2005-07-07 23:21:43 +00:00
Process.cpp	Remove vim settings from source code; people should use llvm/utils/vim/vimrc	2005-05-05 22:33:09 +00:00
Program.cpp	Remove vim settings from source code; people should use llvm/utils/vim/vimrc	2005-05-05 22:33:09 +00:00
README.txt
Signals.cpp	Remove vim settings from source code; people should use llvm/utils/vim/vimrc	2005-05-05 22:33:09 +00:00
TimeValue.cpp	Remove vim settings from source code; people should use llvm/utils/vim/vimrc	2005-05-05 22:33:09 +00:00

README.txt

Design Of lib/System
====================

The software in this directory is designed to completely shield LLVM from any
and all operating system specific functionality. It is not intended to be a
complete operating system wrapper (such as ACE), but only to provide the
functionality necessary to support LLVM.

The software located here, of necessity, has very specific and stringent design
rules. Violation of these rules means that cracks in the shield could form and
the primary goal of the library is defeated. By consistently using this library,
LLVM becomes more easily ported to new platforms since the only thing requiring 
porting is this library.

Complete documentation for the library can be found in the file:
  llvm/docs/SystemLibrary.html 
or at this URL:
  http://llvm.cs.uiuc.edu/docs/SystemLibrary.html

While we recommend that you read the more detailed documentation, for the 
impatient, here's a high level summary of the library's requirements.

 1. No system header files are to be exposed through the interface.
 2. Std C++ and Std C header files are okay to be exposed through the interface.
 3. No exposed system-specific functions.
 4. No exposed system-specific data.
 5. Data in lib/System classes must use only simple C++ intrinsic types.
 6. Errors are handled by throwing std::string *only*.
 7. Library must not throw any exceptions except std::string.
 8. Interface functions must not have throw() specifications.
 9. No duplicate function impementations are permitted within an operating
    system class.

To accomplish these requirements, the library has numerous design criteria that 
must be satisfied. Here's a high level summary of the library's design criteria:

 1. No unused functionality (only what LLVM needs)
 2. High-Level Interfaces
 3. Use Opaque Classes
 4. Common Implementations</a></li>
 5. Multiple Implementations</a></li>
 6. Minimize Memory Allocation</a></li>
 7. No Virtual Methods